Swap items button keeps resetting

Every time I switch from the snapshot to 1.8.8 and back the Swap items button resets to F. I've gone back to before sneaking and my sneak button has stayed the same. I've gone really far back in versions and my controls stay the same, so why not this one?

(Just to clear confusion, when U played the demo I used E as mine and F as inventory so I had to change Swap Items to E.)